[Analgesic effect of COX inhibitors and its mechanism in a rat model of neuropathic pain].

OBJECTIVE To investigate the effect of COX inhibitors on pain threshold and spinal N-methyl-D-aspartate (NMDA) receptor subunit 2B (NR2B) expression in a rat model of neuropathic pain. METHODS Thirty-six male SD rats were randomly divided into sham-operated group, chronic constriction injury (CCI) of the sciatic nerve group, indomethacin+CCI group, and parecoxib+CCI group with corresponding treatments. All the rats were tested for mechanical withdrawal threshold, and at day 13 after the surgery, the rats were decapitated for detection of NR2B expression in the spinal cord at the L4-6 levels. RESULTS The mechanical withdrawal threshold were lowered significantly after the operation in CCI, indomethacin+CCI and parecoxib+CCI groups (P<0.05). Parecoxib alleviated the hypersensitivity of CCI model rats but not affected spinal NR2B expressions (P>0.05). No significant differences were found in the mechanical withdrawal threshold or spinal NR2B expression between CCI group and indomethacin+CCI group (P>0.05). CONCLUSION Parecoxib can alleviate neuropathic hypersensitivity in rats, but this effect may not be associated with NR2B expression in the spinal cord.